Thioglycerol-functionalized CdSe quantum dots detecting cadmium ions

Abstract Water-soluble CdSe quantum dots (QDs) were synthesized using thioglycerol (TG) as the surface capping agent through a one-step process at low temperature T (100 °C). The CdSe quantum dots were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, UV–visible absorption and fluorescence spectroscopies. These measurements revealed that the TG-capped CdSe QDs possess a high crystalline quality with an average diameter in the range 2.5–2.8 nm and exhibit particular optical properties. The UV–visible absorption of CdSe QDs is enhanced by the addition of cadmium ions, with a simultaneous shift of the edge band (400 nm), while seventeen other tested metal cations have no effect on the absorption of QDs. Moreover, the binding of Cd 2+ ions induces a quenching of the fluorescence emission of TG-CdSe QDs. At particular absorption wavelengths, the response is linearly proportional to the cadmium ions concentration ranging from 1.0 to 22 μM with a detection limit of 0.32 μM (37 μg L −1 ). Based on these optical properties, the TG-CdSe QDs could be used as a highly selective probe for the detection of Cd 2+ ions in aqueous solutions, a species highly toxic for cells.